Method for fighting an oilspill in the aftermath of an underwater oil well blowout and installation for carrying out the method

ABSTRACT

A method for pumping away the oil in the aftermath of a blowout in an offshore oil well includes the steps of putting a support structure with a surrounding foil over the leaking oil well or pipe in order to create a hollow space overhead the leaking spot on the sea bottom. Thereafter, pumping water and oil through the top of the support structure for creating an underpressure below the foil, so the foil will be pressed onto the sea bottom due to hydrostatic pressure of the outside water. Then, continuously pumping away the liquid below the foil from within the support structure until it is pure crude oil and collecting the same. A related apparatus includes a support structure with an enclosure for providing a hollow room overhead a leaking spot or oil pipe and a reinforced foil having such size that it extends at least ten meters into the surrounding of the support structure. The reinforced foil is tightly attached to the lower edge of the enclosure of the support structure. A pumping pipe connects to the top of the support structure to pump liquid from within the support structure and lower side of the foil.

This invention concerns a method for fighting oil spills in theaftermath of a blowout, and also an installation for carrying out themethod. A blowout is the uncontrolled release of crude oil or naturalgas or a mixture of the two from a well, typically for petroleumproduction, after pressure control systems have failed. When such anincident occurs, formation fluids begin to flow into the wellbore and upthe annulus and/or inside the drill pipe, and this is commonly called akick. If the well is not shut in (common term for the closing of theblow-out preventer valves), a kick can quickly escalate into a blowoutwhen the formation fluids reach the surface, especially when the fluidis a gas which rapidly expands as it flows up the wellbore, furtherdecreasing the effective weight of the fluid, and accelerates to nearthe speed of sound. The gas and other hydrocarbons commonly igniteduring a blow-out, creating explosions and vigorous fires which aredifficult to extinguish. Blowouts can cause significant damage todrilling rigs, injuries or fatalities to rig personnel, and significantdamage to the environment if hydrocarbons are spilled. Prior to thedevelopment of blow-out preventers, blowouts were common during drillingoperations, and were referred to as gushers. Sometimes, blowouts can beso forceful that they cannot be directly brought under control from thesurface, particularly if there is so much energy in the flowing zonethat it does not deplete significantly over the course of a blowout. Insuch cases, other wells (called relief wells) may be drilled tointersect the well or pocket, in order to allow kill-weight fluids to beintroduced at depth. Contrary to what might be inferred from the term,such wells generally are not used to help relieve pressure usingmultiple outlets from the blowout zone.

An “underground blowout” is a special situation where fluids from highpressure zones flow uncontrolled to lower pressure zones within theopen-hole portion of the wellbore. Usually they come up the wellbore toshallower formations (typically near the last casing shoe) that havebeen fractured from the overall effect of hydrostatic mud head pluscasing pressure imposed at the time of the initial kick. Undergroundblowouts can be very difficult to bring under control although there isno outward flow at the drill site itself. However, if left unchecked, intime the fluids may find their way to the surface elsewhere in thevicinity (possibly “cratering” the rig), or may pressurize other zones,leading to problems when drilling subsequent wells.

A very major blowout occurred on Apr. 20, 2010 approx. 135 sea miles(250 km) south east of New Orleans in the Mexican Gulf. And it was avery special case since the blowout occurred very deep in the sea, andoil leaked out of the hole in a depth of 5000 ft or approx. 1500 meters.It is estimated that up to 10 million litres or 10,000 m³ of oil per daywere being spilled into the ocean from underground or from broken drillpipes near the hole, which caused a dramatic disaster for theenvironment of an entire large region.

There are no experienced and demonstrated techniques available in orderto stop such an enormous spill of oil and the obstacles to stop suchuncontrolled flow of oil are tremendous since the leaks are located 1500m below sea level on the hole. The oil formations from where the oil wastaken out are located approx. 18,000 ft or approx. 5,500 m below sealevel, that is some 13,000 ft or approx. 4,000 m below hole in theunderground. Relief borings from the side have been brought down inorder to reach the leaking oil well pipe, open it there and pump greatamounts of mud at high pressure into it in order to block it by theweight of this pumped in material. However, to bring down such reliefborings is time consuming. And even if the mud would arrive at theleaking oil pipe, the mud could not prevent a leaking that occursthrough slits and cracks around the pipe and up the annulus or throughnatural cracks in the formation which may have occurred due todetonations in the underground.

Another proposal was to put a domelike shell made of steel or reinforcedconcrete on top of the leaking points and evacuate their content andthereby creating a big pressure onto the outer side of the shell andkeep it in place, and then continuously pump the inflowing oil to thesurface. However, underground streams and waves created heavy problemsfor this undertaking, and due to the low temperatures, freezing ofvalves created severe problems.

The purpose of this invention is to present a method by which such aleaking of oil from the hole and from well pipes can be foughtsuccessfully so that the oil spill into the water can be stopped andprevent devastating consequences for the environment. A further purposeis to teach an installation which allows it to carry out this methodeven at great depths, that is deep in the sea on the hole.

The method according to claim 1 and the installation according to claim5 are being presented in the following, by the example of the recentheavy blowout in the Mexican gulf. The method comprises several stepsand is promising for successfully deal with that enormous problem andget the oil leaking into the water eventually stopped completely.

10,000 m³ of oil per day equals to roughly 375 tons per hour, or 104 kgper second. This is the proximate mass flow that has to be dealt with.But this method has the potential to keep up with an even substantiallygreater flux of oil. In the accident in the Mexican gulf, the oil has aninitial temperature of approx. 80° C. and originates from sea bottom atdepths of approx. 18,000 ft or 5500 m below sea level. At such depthsthere is an enormous hydrostatic pressure of approx. 550 bar or evenmore acting. Apparently, there were several leaks—such ones in thecollapsed oil well pipes—and further leaks of oil in the hole where theoil escapes through several cracks.

This present method is in essence a low tech method, and thereforequickly to apply, at low cost, and it does prevent the further spillingof oil into the sea water. With the exception of some rare specialcases, this method will allow to pump pure crude oil after an initialphase of executing the method. Although the method is not thought to bea permanent solution, it can be in operation several months in order tobridge the time it takes to bring down release borings and put them inoperation.

The installation for execution of the method is suitable to serve as anemergency equipment and may be built in advance for future incidentsshould they ever occur. There are hundreds of deep sea borings inoperation and therefore, a situation as the one which occurred in theGulf of Mexico might occur on other sites in the future.

The method can be carried out no matter whether the leaking of the oilis from a broken pipe over the hole or comes out of the sea bottomthrough open cracks. The method will now be described and its operationexplained by reference to the accompanying drawings. These figures show:

FIG. 1: The overall situation of a underwater oil spill with theinstallation for executing the method;

FIG. 2: The three-leg pyramid-like steel support;

FIG. 3: A section view of the three-leg support structure and theadjacent covering foil on the sea bottom, with the detail of itsattachment to the support;

FIG. 4: The stabilization of the three-leg support and foil on the seabottom, seen from above;

FIG. 5: The connection of the pumping pipe with the top of the supportstructure;

FIG. 6: A side view of several steps to lowering down the foil and thesupport structure to the sea bottom;

FIG. 7: A side view of an alternative method for lowering down thesupport structure and foil to the sea bottom.

This method is suitable for leaking pipes over the level of the seabottom as well as for situations where the oil is leaking out of the seabottom through cracks since a pipe did break below sea bottom or therewas a bursting out of oil through natural channels. The method does makeuse of the hydrostatic pressure difference between the static pressureat the sea bottom and the reduced pressure in a hollow room created atthe sea bottom of which liquid is pumped out. If oil and water is beingpumped out of such an artificially created hollow room over the seabottom, at a pressure drop of merely 50 kPa (0.5 bar), the pressure fromoutside will amount to 50 kN/m².

For realizing this method, a support structure or bearing supporttogether with a reinforced foil are the key elements of theinstallation. The entire installation is shown in FIG. 1. The supportstructure 4 is a steel construction in the form of a three-legpyramid-like steel structure which is covered and completely enclosed bystrong steel plates 17 and this support structure 4 or support structurehas three legs 2 so it always stands safely and in a definite positionon any ground 10. The legs 2 are equipped each with a foot 3 that canswivel in any direction around the leg 2 end so the feet 3 will adapt toany underground surface and provide stability for the entire structure.The three legs 2 keep the entire support structure in a stable positionso it can carry much load. The size of this support structure 4 may varyaccording the situation on site, e.g. the legs 2 stand on a circle ofseveral meters in diameter, at least large enough in order to completelyenclose the leaking spot, that is e.g. a crack 19 in the sea bottom, ora pipe 26 that was broken. The height of this support structure 4measures anything between approx. 3 and 15 meters, in special cases theheight may be even higher, and the side length at the bottom will beapprox. 10 meters. In any case, the most important point is that thissupport structure 4 will cover the entire spot where oil is leaking outinto the sea water.

On this support structure 4, a strong reinforced, water tight, oil andsea-water resistant foil 1 is being connected along the lower edge 33 ofthe pyramid-like structure 4. The foil 1 can be composed of a number ofstrips that are being welded or glued together along their edges. Thefoil 1 is reincored by a steel fabric or by a carbon-fabric in itsinterior. This foil 1 is finally lying on the sea bottom around thesupport structure 4. The foil 1 has in its center a hole of triangularshape which is being put over the neck of the support structure 4 so theinner edge of said hole will fit to the lower edge 33 of steel plates 17on the structure. The foil 1 is securely attached on the lower edge 33of the steel plates 17 that cover the structure and hence the foil 1covers the entire surroundings of the structure. At its periphery orouter edge, a surrounding frame 5 made of strong steel tubes or profilesis being placed in order to keep the position of the foil 1 on the seabottom 10 and to keep it stretched. This frame 5 can form a circle, asquare, a triangle or have a rectangular shape when seen from above.Alternatively, blocks 34 of concrete can be placed, one after the other,in a row along the outer edge of the foil 1, as shown in FIG. 4.

A pipe 6,7 coming from a tanker ship 9 on the surface of the sea can beconnected with a pipe neck that is extending out of the top of thesupport structure 4 and once the connection is established, liquid canbe pumped from below the structure 4 and foil 1 to the sea surface intotanks of a tanker ship 9. Since the depth at which the installation isbeing placed may be several hundred or even thousand meters deep,several underwater pumps 8 will be used since sucking is only possibleover somewhat less than 10 meters height. The power of these pumps 8 areregulated by their revolution per minute, according to the differencebetween the pressure inside and outside the support structure 4 and tokeep that difference constant in a certain range. By using underwaterpumps 8, the liquid can be pressed with high pressures onto the surfaceof the sea. Several pumps 8 can be installed over the entire distancewhich even act parallel in order to establish a redundancy. As soon asthe pressure within that pipe 6,7 and hence in the room within thesupport structure 4 is dropped to a pressure lower than the pressureacting outside of the foil and structure, the foil 1 is being pressedwith enormous forces to the sea bottom and also the support structure 4is being pressed onto the sea bottom since the hydrostatic pressure ofthe sea water will cause that pressing force. If the pressure within thesupport structure 4 and underneath the foil 1 is merely lowered ataround 0.5 bar, the pressure which then acts from outside is about 50kN/m² and this pressure causes the foil 1 to be pressed to the seabottom and the pressure also acts on the plates 17 which enclose theentire support structure 4. This will keep the structure 4 and adjacentfoil 1 in place no matter what happens. The foil 1 and support structure4 will even resist substantial underground streams. The foil 1 islikewise pressed onto the sea bottom 10 and hence follows the form andshape of its surface. Even if some water is leaking from the outer edgeunderneath the foil 1 toward its center, the force which does press thefoil 1 onto the sea bottom is substantial, although it does slightlydecrease toward the outer edge of the foil 1. At all times the pressurewithin the support structure 4 and underneath the foil 1 will be keptlower than the outside acting water pressure. This will cause the entireinstallation to rest absolutely stable on the sea bottom.

In FIG. 2, the support structure 4 on the sea bottom 10 is shown in aperspective view. Reinforcement struts 20 or bars are welded into thelower side of the bearing support 4 in order to strengthen its loadcapacity and in order to provide a support structure for the steelplates 17 to be fixed around the support structure 4 so they willcompletely enclose it and ultimately form the outer side of thestructure. The lower edge of the steel plates 17 will be positionedapprox. 0.5 m to 1.5 m above sea ground 10 so it will not touch it evenif the sea bottom is uneven. The foil 1 will be connected tightly to thelower edge of the steel plates 17 and from there extend on to thesurrounding sea bottom 10. On the top of the structure, the neck 21 isshown which does communicate with the inner side of the supportstructure 4.

In FIG. 3, further details of the support structure 4 and foil 1 arebeing shown. The structure 4 may be equipped with an electrical heatinginstallation 30 in order to keep the seawater which is mixing with thespilled oil warm enough for pumping. On the lower edge 33 of the steelplates 17, the foil 1 is tightly attached. This is shown here on theleft side of the structure by way of example. As shonw in the respectiveenlarged view, a clamping device 35 holds a steel plate 32 which isslightly bent upwards. Along the lower surface of this steel plate 32,the foil 1 will smoothly adapt when the entire structure and attachedfoil will be lowered down onto the sea bottom as will be explainedlater. Underneath this bent steel plate 32, there is a flexibledeflecting steel plate 31 which is bent toward the sea bottom. Betweenthese two steel plates 31,32, the reinforced foil 1 is clamped by theclamping device 35 and thereby securely attached to the structure 4.When the structure 4 is lowered from a ship down to the sea bottom, thesurrounding flexible steel plates 31 adapt to the uneven sea bottom andthere outer edge will lay on the sea bottom. The outer edge of the foil1 is attached to a frame 5 made of strong steel pipes or profiles. Thisframe 5 forms a circle with a radius of approx. 10 meters, or a square,triangle or rectangle with a side length of approx. 20 meters around theentire support structure 4 and the attached foil 1 and keeps the foil 1stretched at all times.

In FIG. 4, the support structure 4, foil 1 and the surrounding frame 5are shown from above, laying on the sea bottom. The corners of the frame5 are stabilized by cables 36 which are attached to concrete blocks 34positioned on the sea bottom. Further blocks 18 can be put onto the edgeof the foil 1. In FIG. 5, the connection of the pumping pipe 6 with thetop of the foil 1 on the support structure 4 or support structure isshown. The neck 21 comes through the steel plate 17 on top of thestructure 4. A conical connecting piece 16 is put over the neck 21 andwill be sucked onto the steel plate 17 once the pressure within thesupport structure 4 is lower than the outside pressure of the seawater.The connecting piece is followed by a pipe with a flange 14 at its end.To this flange 14, another one is fixed which is connected to a strongrubber bellow 15 which provides a certain flexibility. This rubberbellow pipe 15 may have a steel spring in its interior in order towithstand the pressure difference between outside and inside. Thepumping pipe 6 is connected to the upper flange 13 of the rubber bellow15. The pumping pipe 6 can therefore move a certain distance in anydirection and also its direction may vary from the straight upwarddirection. This pumping pipe 6 may be equipped with electrical heatingmeans, e.g. a heating coil surrounding the pipe 6 over the initialsection in order to prevent a freezing of the pumped liquids due to thelowered pressure and the low temperature of the surrounding sea water.

FIG. 6 does show in a schematic view how the reinforced foil 1 with thesupport structure 4 being attached to it is brought down onto the seabottom. Typically, three or even four or more ships are being used whichdo cooperate with each other. They are equipped with winches with longsteel cables 22. The ends of these steel cables 22 are fixed to theframe 5 with the reinforced foil 1 attached to it and the entireinstallation will be lowered down within the sea in a generallyhorizontal position. Therefore the ships must pull their cables radiallyaway from a definite center and contemporarily lowering their cablesfrom their winches. A strong steel cable 24 may be used as a guidingcable so the structure 4 hanging on the foil 1 will be directed to thespilling spot on the sea bottom. The cable 24 hangs on a swimmer 23 andthe edge of the hole 25 in the structure 4 is made of a strong steelring in order to prevent the structure 4 to be damaged. At the lowerend, the cable 24 is fixed on a concrete block that has been positionedin advance. Therefore, the structure 4 and foil 1 will be perfectlyguided with the central hole 25 of the structure. Once, the structure 4and foil 1 are positioned on the sea bottom, the pumping pipe will bedirected with its conical connecting piece 16 over the neck 21. Then,the pumping can start which will help cause the foil 1 to be suckedtightly around the support structure 4 and onto the sea bottom. Thepumping pipe 6 and its connecting piece may likewise be put over theneck 21 by using guiding cables which are fixed on top of the supportstructure 4.

FIG. 7 shows an alternate way to bring down the support structure 4 andthe foil 1. Four or even more ships are being used which do cooperatewith each other. They first lower down heavy weights 27 hanging on aloose roll 28. This weights may be concrete blocks 27 of several tons ofweight. These weights 27 are being positioned exactly around the spotwhere the support structure 4 needs to be positioned on the sea bottom10. They then have a definite distance from that selected spot. Once theweights 27 are in position, the cables 29 going around the loose rolls28 on the weights 27 will serve as guiding cables for lowering down thesupport structure 4 and the foil 1. E.g. for such weights and guidingstrings can be used, or even more which are positioned overhead the edgeof the foil 1 when it is finally down on the bottom of the sea. Thesupport structure 4 can fixed to the foil 1 so it will furtheron hang onthe center of the foil 1. The connection to the pumping pipe 6 is thenalready established. The foil 1 can then be lowered down, contemporarilywith the support structure 4 hanging on it. One pipe piece of thepumping pipe after the other will be installed as the lowering downproceeds. The frame 5 around the foil 1 is attached via holding elementswhich are fixed on the cables 29 of each guiding string. By this, thefoil 1 can be held almost horizontal and stretched and can be lowereddown in completely controlled manner. This also facilitates the task tobring the support structure 4 exactly over the leaking pipe on the seabottom since the foil and the support structure 4 are precisely guidedalong the stretched vertical cables 29 going down do definite points.Once the support structure 4 is close to the leaking spot, e.g. severalmeters, the pumps are activated and start to pump liquid from theinterior of the support structure. Once the support structure 4 is layedonto the sea bottom and finds a definite stand, the foil 1 is completelylowered down on the sea bottom as well and the pumping out of liquidthrough the top neck of the support structure 4, the foil 1 will betightly sucked to the outer surface of the support structure and also tothe surrounding sea bottom.

Once the pumps are active, the pressure in the interior of the supportstructure 4 and underneath the foil 1 will at all times be kept lowerthan the outside water pressure. This will keep the structure and foil 1in place and the oil is being sucked out of the created hollow room andpumped to the surface. A further spilling of oil into the sea water isprevented and time is gained for bringing release borings down andeventually shut down the well in a conventionally and approved manner.

1-13. (canceled)
 14. A method for pumping away the oil in the aftermathof a blow out in an offshore oil well, comprising the steps of: puttingan installation made of a support structure with an enclosure and anattached reinforced foil extending horizontally into its surrounding,over a leaking oil well or pipe; pumping water and oil out of aninterior of the support structure for creating an underpressureunderneath support structure and the covering foil, so that the supportstructure and the foil will be pressed onto the sea bottom due tohydrostatic pressure of outside water; continuously pumping away liquidfrom the interior of the support structure, and therefore from below thefoil, until it is pure crude oil; and, collecting the pure crude oil ina tank ship.
 15. A method for pumping away the oil in the aftermath of ablow out in an offshore oil well according to claim 14, furthercomprising the steps of putting a weight block on a guiding string onthe leaking oil well or pipe for serving as a guide for lowering aninstallation down onto the sea bottom; lowering the installation made ofa support structure with enclosure and an attached reinforced foilextending horizontally to a frame over the leaking oil well or pipealong the guiding string by at least three ships with the frame, foiland support structure hanging on steel cables attached to the frame,while the cables come from winches installed on the ships, while theships pull in a radial direction from a center overhead the supportstructure on the sea bottom, and the support structure being guided byat least one guiding cable fixed on a weight block on the sea bottom andhanging on a swimmer; putting the pumping pipe with its conicalconnecting piece over the neck on the support structure and then pumpingwater and oil through the top of support structure and from underneaththe reinforced foil for creating an underpressure underneath the foil,so the foil will be pressed onto the sea bottom due to hydrostaticpressure of the outside water; and, continuously pumping away the liquidfrom the interior of the support structure, and therefore from below thefoil, until the oil well pipe is blocked.
 16. The method for pumpingaway the oil in the aftermath of a blow out in an offshore oil wellaccording to claim 14, wherein the lowering of the frame, the foil withthe support structure and the connecting of the pumping pipe is enabledby guiding cables stretched between the weight block and a swimmer ontop of the sea along by which the entire installation and the pumpingpipe are being guided when lowered down and until put in operation. 17.A method for pumping away the oil in the aftermath of a blow out in anoffshore oil well, comprising the steps of: putting a support structurewith an enclosure and a reinforced foil attached to its lower edge andwith the foil being surrounded by a frame to which it is fixed, over theleaking oil well or pipe, so that the support structure and the foilwith its frame are lowered downwardly contemporarily along at least oneguiding string leading to a weight positioned on a sea bottom; pumpingwater and oil through the reinforced foil for creating an underpressureunderneath the foil, so the foil will be pressed onto the supportstructure and the sea bottom due to hydrostatic pressure of the outsidewater; and, continuously pumping away liquid from an interior of thesupport structure, and therefore from below the foil, until it is purecrude oil; and, collecting the pure crude oil in a tank ship.
 18. Themethod for pumping away the oil in the aftermath of a blow out in anoffshore oil well according to claim 17, wherein the lowering of theframe, the foil with the support structure and the connecting of thepumping pipe is enabled by guiding cables stretched between the weightblock and a swimmer on top of the sea along by which the entireinstallation and the pumping pipe are being guided when lowered down anduntil put in operation.
 19. An apparatus for pumping away oil in theaftermath of a blow out in an offshore oil well, comprising: a supportstructure with an enclosure for providing a hollow room overhead aleaking spot or oil pipe; a reinforced foil extending at least tenmeters into a surrounding of the support structure and attached to alower edge of the enclosure of the support structure; and, a pumpingpipe connectable to a top of the support structure for pumping liquidfrom within the support structure and a lower side of the foil.
 20. Theapparatus for pumping away the oil in the aftermath of a blow out in anoffshore oil well according to claim 19, wherein the support structureis enclosed with an enclosure made of steel plates, the steel platesbeing fixed on the support structure and on a plurality of struts forreinforcing the support structure and providing a structure for fixingsaid steel plates.
 21. The apparatus for pumping away the oil in theaftermath of a blow out in an offshore oil well according to claim 19,wherein the support structure has at least three legs with each leg ofthe at least three legs being equipped with a swivel-able foot.
 22. Theapparatus for pumping away the oil in the aftermath of a blow out in anoffshore oil well according to claim 19, wherein the support structureis equipped with a neck extending upwards from its top for establishinga connection to a pumping pipe.
 23. The apparatus for pumping away theoil in the aftermath of a blow out in an offshore oil well according toclaim 19, wherein the reinforced foil has a circular shape and is madeof a steel- or carbon-fiber reinforced plastic foil.
 24. The apparatusfor pumping away the oil in the aftermath of a blow out in an offshoreoil well according to claim 19, wherein the reinforced foil has a squareshape and is made of a steel- or carbon-fiber reinforced plastic foil.25. The apparatus for pumping away the oil in the aftermath of a blowout in an offshore oil well according to claim 19, wherein thereinforced foil is a steel- or carbon-fiber reinforced plastic foil witha further reinforced edge and a frame surrounding the foil and on whichsaid frame, an outer edge of the foil is securely attached to saidframe.
 26. The apparatus for pumping away the oil in the aftermath of ablow out in an offshore oil well according to claim 19, wherein a loweredge the enclosure of the support structure is equipped with clampingdevices for clamping a steel plate extending horizontally from thesupport structure and being bent upwards, and for further clampingflexible steel plates bent downwards for adapting to a sea bottom, andbetween said flexible steel plates, for clamping the reinforced foil.27. The apparatus for pumping away the oil in the aftermath of a blowout in an offshore oil well according to claim 19, wherein the pumpingpipe is equipped on its lower end with a flexible reinforced rubberbellow pipe for a flexible connection to a neck on the supportstructure, and is further equipped with a heater for preventing afreezing of pumped liquid.
 28. The apparatus for pumping away the oil inthe aftermath of a blow out in an offshore oil well according to claim19, wherein the interior of the support structure is equipped with anelectrical heating installation.